A conventional package structure includes a substrate and a chip disposed on the substrate, wherein the chip is covered completely by a heat dissipation sheet to make the chip being within a completely sealed space formed between the heat dissipation sheet and the substrate for heat dissipation. However, air is also covered in the completely sealed space in coverage process to lead the thermal energy generated from the chip expand air volume in the completely sealed space. The expanding air will cause warpage and deformation of the heat dissipation sheet to make the heat dissipation sheet separate from the chip or the substrate, so as to damage the package structure or low heat dissipation efficiency of the chip.